Fix events list default closed filter

[DeepCogNeural]

Summary

• Make events list send closed=false by default when neither --closed nor --active is provided.
• Keep explicit --closed behavior and the existing --active to closed mapping.
• Add a focused unit test for the resolved closed filter, covering default behavior, explicit --closed, --active true, --active false, and --closed precedence.

Why

Gamma /events currently returns closed events when the closed query parameter is omitted. The CLI should request open events by default.

Fixes #71

Validation

• cargo fmt --check
• cargo clippy -- -D warnings
• cargo test

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Note

Low Risk
Localized CLI query-parameter default for events listing; no auth or data-path changes.

Overview
events list now always sends an explicit closed query parameter instead of omitting it when neither --closed nor --active is set. The default is closed=false (open events), matching expected CLI behavior when Gamma returns closed events if closed is missing.

List request construction is moved into build_events_list_request, which resolves filters as: explicit --closed wins; otherwise --active maps to closed = !active; otherwise false. --active / --closed combinations from before are preserved (e.g. --active alone still implies closed=false).

A unit test (events_list_resolves_closed_filter) locks in those resolution cases.

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